This study determined the oxygen uptake response to short and long intermittent high intensity cycle exercise in average fit college aged women. Female subjects (N = 6; 18-29 yr) underwent three exercise cycle ergometer testing sessions: a peak oxygen uptake and lactate test, 20 minutes of short high intermittent intensity exercise (8-s sprint, 12-s recovery), and 20 minutes of long high intermittent intensity exercise (24-s sprint, 36-s recovery). On separate days power outputs eliciting energy expenditures at an RER of .93 were continued for 20 minutes in either the 8 s or 24 s sprint condition. Blood samples were collected from an antecubital vein at rest and every 5 minute during exercise. Ventilatory, heart rate, and lactate measures were recorded throughout the exercises.

Average exercise heart rate and lactate were similar for both the 8- and 24-s conditions. However, for the 8-s sprint oxygen uptake was significantly higher than that of the 24-s sprint. Twenty minutes of 8-s sprint, 12-s recovery high intermittent intensity cycle exercise resulted in similar heart rate and lactate responses but significantly greater oxygen uptake compared to a 24-s sprint, 36-s recovery exercise bout. Thus, despite both conditions having the same total amount of exercise the shorter exercise bout resulted in significantly greater energy expenditure.

Implication. Short work and rest ratios produce greater energy expenditure than long work and rest periods.